Eyeball Flashcards
The eyeball is located in the bony socket called the ________
Orbit
The ADNEXA (accessory ocular structures of the eye) are
Palpebrae (eyelid)
Third eyelid and conjunctiva
Lacrimal apparatus
What are the tunics of the eye
Fibrous
Vascular
Retinal
The fibrous tunic is made of of what three things?
Sclera
Cornea
Limbus (corneoscleral junction)
What is the sclera
Posterior portion of the eye
White opaque layer of dense irregular CT
What is the function of the sclera
Protect
Maintain shape
Insertion point for extraocular muscle s
What is the cornea?
Anterior portion of the eye
Avascular and transparent convex-concave lens
What are the 5 layers of the cornea??
1 Anterior corneal epithelium (stratified squamous)
2 Anterior limiting lamina/ subepithelial basement membrane (parallel collagen fibers)
3 substantia propria -corneal stroma
4 posterior limiting lamina- Descemets membrane
5 posterior epithelium of cornea
What factors contribute to corneal transparency
Avascular
Collagen arrangement
Proteoglycans between collagen
Na+ pumps to transport water out
What is the limbus?
Corneoscleral junction
Where the opaque sclera overlaps the transparent cornea
The vascular tunic of the eye is composed of?
Iris
Iridocorneal angle
Ciliary body
Choroid
The stroma of the iris is made of of what?
Pigmented loose connective tissue and Iridial melanin
The posterior epithelium of the iris contains ___________________ in equids and ruminants
Iridic granules (corpora nigra)
The ______________ lies at the convergence of the corneoscleral junction and ciliary body
Iridocorneal angle
The Iridocorneal angle is composed of ? What is its purpose?
Pectinate ligaments
Trabecular mesh work
And trabecular veins
This is the draining point for aqueous humor
The anterior expansion of the choroid at the level of the lens is the _________
Ciliary body
What is the mechanical function of the ciliary body?
Contracts to reduce tension in zonular fibers of the lens
Describe the epithelial surface of the ciliary processes of the ciliary body
Non pigmented -ion transporting forming aqueous humor
Pigmented- basement membrane extends to form zonular fibers that suspend the lens
Hwo does the iris transition into the ciliary body?
Posterior pigmented epithelium is continuous with the non-pigmented epithelium of the ciliary body
Aqueous humor occupies what space?
Anterior and posterior chambers
What is the drainage pathway for aqueous humor ?
Posterior chamber -> pupil -> Anterior chamber -> iridocorneal angle -> pectinate ligaments -> scleral venous plexus
What is the choroid?
Posterior portion of the vascular tunic
The anterior portion of the choroid is continuous with the _____________
Ciliary body
The dorsal part of the choroid is made of what?
And what is its purpose
Tapetum lucidum
Increase light perception under conditions of poor illumination
The neuroepithelial/ retinal tunic is made up of which three parts?
Sensory/optical part
Non-sensory/ciliary part
Non-sensory/iridal part
The sensory/ optical retina is in contact with what layer of the eye?
Choroid
What holds the retinal tunic in place?
Vitreous body
What are the layers of the sensory/optical retina?
Optic nerve fibers Ganglionic layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Cell bodies of rods and cones Photoreceptors layer Pigment cells
What is the pathway of optical nerve impulse travel?
Light passes through retina to stimulate the photoreceptors cells (rods and cones)
Impulse passes to bipolar neurons
To ganglion cells
Axons of ganglion cells for nerve fiber layer and converge at optic disk
What is the path of light to the retina
Through tear film Cornea Aqueous humor Pupil Lens Vitreous humor First 8 layers of retina Rods and cones Absorbed by retinal epithelium
Retinal pigmented epithelium
Outermost layer of retina
Flat polygonal cells resting on a BM
Transport of nutrients and metabolites to the rods and cones
Compare rods and cones
Rods
- inner segment long and thin
- flattened membranous disk with Rhodopsin
- dim light vision
Cones
- inner segment has broad base
- disks with Iodopisn
- bright light and colour vision
Where does retinal detachment occur?
Between rods and cones and pigmented retinal epithelium
What is the vitreous body made of??
Water and hyaluronic acid
Gel cortex with liquid center
What is the structure of the lens?
Entirely surrounded by capsule - thicker on anterior surface
What suspends the lens
Zonular fibers
The anterior epithelium of the lens is made up of ______________ cells which become elongate at the equator
Simple cuboidal
The anterior epithelium cells differentiate into?
Elongate lens fibers
-prism like cells that lack nuclei and have many gap junctions
The eyelid is made up of?
Conjunctiva Cilia (eyelashes) Tarsal (meibomian) glands Third eyelid (nictitating membrane) Lacrima (tear) apparatus
The __________ conjunctiva lines the inner eyelid and the ____________ conjunctiva lines the sclera
Palpebral
Bulbar
Conjunctiva is a _______________ epithelium
Pseudostratified columnar or transitional that becomes squamous at eyelid margin
What is the purpose of the third eyelid?
Protects eye
Remove foreign material
The third eyelid is a fold of the __________ formed by hyaline cartilage (ruminants) and elastic cartilage (dog)
Conjunctiva
What are located under the conjunctival surface?
Lymphatic nodules
Lacrimal glands are _________________ acini composed of serectory granular cells
Tubuloalveolar seromucinous
Tears are produced by which three glands?
Meibomian (tarsal) - oily superficial
Lacrimal - sero-mucous (from third eyelid)
Mucous - from goblet cells of conjuring
